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Hypertension and heart damage

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Tanner Marshall.

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  • male robot hal style avatar for user Leon Hinchcliffe
    why is it hypertrophy not cardiomegaly?
    (3 votes)
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    • primosaur ultimate style avatar for user Swift Runner
      Hypertrophic cardiomyopathy (HCM) is a form of cardiomyopathy in which the walls of the heart's chambers thicken abnormally. Other names for hypertrophic cardiomyopathy are idiopathic hypertrophic subaortic stenosis (IHSS); Hypertensive hypertrophic cardiomyopathy; and asymmetrical septal hypertrophy.

      Hypertrophic cardiomyopathy usually appears in young people, often in athletes. For this reason it is sometimes called athletic heart muscle disease. However, people of any age can develop hypertrophic cardiomyopathy. The American Heart Association reports that 36% of young athletes who die suddenly have probable or definite hypertrophic cardiomyopathy. Hypertrophic cardiomyopathy is the result of abnormal growth of the heart muscle cells. The wall between the heart's chambers (the septum) may become so thickened that it blocks the flow of blood through the lower left chamber (left ventricle). The thickened wall may push on the heart valve between the two left heart chambers (mitral valve), making it leaky. The thickened muscle walls also prevent the heart from stretching as much as it should to fill with blood.

      Cardiomegaly: A medical term ending in "-megaly" indicates abnormal enlargement of the organ or structure referred to in the first part of the word. Cardio refers to the heart. Hence, cardiomegaly means an enlarged heart. (Cardiomegaly is also called megalocardia.)
      (3 votes)
  • starky sapling style avatar for user elizabeth
    if you increase the pressure on the veinous side, does the heart have to pump harder? he only talks about the arterial side.
    (2 votes)
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    • leafers seed style avatar for user PCMSIII
      When we think about pressure that the heart has to pump against, we think about the pressure that each ventricle sees. The left ventricle (LV) sees the peripheral resistance of the arteries. This is called the "afterload." The right ventricle (RV) also has an afterload, but in the case of the human heart, the "right after load" is the pulmonary vasculature. The pulmonary circulation is under much much less pressure as compared to the left/systemic side. (10-15 mmHg vs. 100-150 mmHg) This pressure usually doesn't change too much. It goes down when we breathe in and fill our lungs with air. When we do that, we take the pressure off of the pulmonary arteries that run through our lungs, decreasing the resistance, and therefore decreasing right "after load".

      Normally, we don't think about after load on the right side given the fact that under normal conditions its almost negligible. (That's why the right ventricle is a lot smaller and less muscular than the left ventricle.) There are some disease states, however, that increase right after load and cause right sided heart failure. Pulmonary arterial hypertension is kind of like the traditional systemic type of hypertension. This famously causes right sided heart failure due to increased after load. The most common cause of right sided failure, however, is left sided heart failure! Think about it. If the left side of the heart isn't pumping well, then blood is going to pool in the left ventricle and eventually back up from the left atrium and back into the pulmonary veins. From here, the excess fluid in the lungs is going to cause the right heart to push against all this blood, increasing the pressure that the right heart sees. This leads to right sided heart failure.
      (5 votes)
  • blobby green style avatar for user Jess Kydd-Coutts
    How does obesity cause hypertension?
    (3 votes)
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    • hopper cool style avatar for user SofiyaMarkova
      fat cells need oxygen too, so the extra cells demand more blood flow. they also press on the arteries causing higher resistance.

      obesity is usually accompanied with other health problems since and obese person probably eats food that causes atherosclerosis and therefore it increases blood pressure because of the plaque build up.
      (2 votes)
  • blobby green style avatar for user George Kung
    will going gym result in hypertrophy?
    (2 votes)
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    • aqualine ultimate style avatar for user Sterre
      Only if you exercise excessively, a normal amount of moderate exercise (going to the gym maybe a couple times a week and not pushing yourself too hard) shouldn't. It's not uncommon to see hypertophy of the heart muscle in professional athletes, especially runners and people who do a lot of cardio every day.
      (2 votes)

Video transcript

- [Voiceover] All right, so it's really important to keep your blood pressure under control. If it's not under control and you let it get too high, this extra pressure that's not supposed to be there starts to damage the whole plumbing system. Higher pressures can both damage the pump, which is your heart, and the pipes, which are like your arteries and your veins. And if these two supply systems become damaged, the organs they supply can also be damaged, which is not good. So let's think about this, you've got this arterial pressure coming out of the pump, and then this venous pressure coming into the pump, right? Well what happens on the arterial side? Well the heart pumps blood out. Since there's this pressure though, the heart has to basically pump hard enough to generate its own opposing pressure that overcomes this arterial pressure in order to actually get this blood moving around our system. So let's remember that the two factors that affect pressure in the blood vessels are flow, which is related to the volume of blood circulating around the body, and then the resistance, which makes it more difficult for blood to move around. So increasing either flow or resistance also increases our pressure, right? Well, there's actually an equation that relates these three guys, and that's the following. So you have your pressure out, which is the same as our arterial pressure, minus the pressure in, which is like our venous pressure, and is usually way lower than the arterial pressure. And that is equal to the flow times the resistance. So let's map these guys out. As we move from pressure out from the arteries to pressure in from the veins, we're gonna run into some resistances. We have some resistance, R, from the arteries, and then a lot more from the arterials, which are like these smaller branches of the arteries. And remember when the pipes get smaller, our resistance actually goes up, right? And then finally, after those arterials, we get to the capillaries, which are like the smallest, tiny little pipes that give blood to your tissues. After the capillaries, they get bigger, and then come back to your heart through your veins. Until finally you get a little more resistance from your veins, but not much. So that's the resistance, but let's not forget to also add this flow of blood circulating around, which is a certain volume of blood moving per minute, which is our flow. So from the equation if you increase the flow, you increase the pressure, or if you increase the resistances, say your arteries get narrower, you also increase the pressure. So anything that increases our pressure on the arterial side is gonna make our heart have to pump harder, right, since it has to overcome this increased arterial pressure. So if this pressure goes up, what do we do? Well, let's think about that, what's one way we could pump harder through our plumbing system? Well, we can try to invest in a bigger pump, right? Well, that's not too far off, actually, because what happens when your heart needs to pump harder is that its muscles actually get bigger, which is called hypertrophy. And at first you might think, hey, that doesn't sound so bad, it's like when I go to the gym and bulk up my biceps. And it kind of is, so much so that it changes shape just like your biceps, but when your heart changes shape and hypertrophies, it actually ends up pumping less effectively, so it's a less efficient pump. If we take a look at all the chambers of your heart, you've got the right atrium up top right, which lets blood down into the right ventricle and then the left atrium up top left, which goes down into the left ventricle. And it's this left ventricle that does the pumping out to the body, so it's this guy that usually tries to bulk up and gain muscle to beat out that arterial pressure. Not only does this extra muscle cause the heart to pump less effectively, as you can sort of see, there's also less room in the chamber to fill with blood. So now there's even less blood being pumped out with each beat, and so less blood is delivered to the body and the organs. So as both the filling volume and the pumping ability decreases, our bigger and bulkier pump isn't going to do as good of a job in giving our body blood, right? And when this happens, it can be considered this early manifestation of heart failure, which as we've seen is a result of a higher arterial blood pressure.